Ahead of the official releases of both the iPhone 5s and iPhone 5c this Friday, September 20th, early reviews of the new devices have gone live at several publications. The iPhone 5s includes notable new featured such as the Touch ID fingerprint authentication system, and improved camera, and a faster processor.

In my scores of tests, with three fingers, the reader never failed me and none of the 20 or so people I asked to test it was able to unlock the phone. If a finger match fails three times, the phone offers you a chance to type in your passcode instead. After five failures, it requires the passcode. Apple says the odds another person’s finger would work are 1 in 50,000, versus 1 in 10,000 for breaking a four-digit passcode.

There is one bug in the system: Sometimes, while trying to use a finger to authenticate an online purchase, the phone asks for a password. Apple says it expects to fix this bug very quickly.

On A7 chip:

The iPhone 5S boasts something called a 64-bit processor, which means the system can process data in bigger chunks, and thus much faster. But I didn’t notice any dramatic speed improvement, partly because few apps have yet to be rewritten to take advantage of it.

On calls:

Voice calls were excellent, even over Bluetooth in a car. I didn’t do a formal battery test, but the iPhone 5S lasted a full workday, including one day where it still had 15% of battery left after 14 hours.

It’s just slightly thicker and heavier than the iPhone 5. And while the 5C isn’t as refined-looking as the iPhone 5 or the new 5S, it isn’t a tacky plastic phone, either. I’ve tested plastic phones before, including the Samsung Galaxy S4 and the new Moto X from Motorola, and this phone feels more solid in the hand. Call quality was good.

Apple has put a larger battery in the 5C, though the company has declined to say exactly how much bigger it is. Since the display and processor remain the same, a user should be able to get some extra juice with this phone.

This past weekend I used both the 5C and my own iPhone 5 at the same time, with the display on both set to about 75% of full brightness and their batteries fully charged. I ran the same apps, including maps apps, browsed through both Safari browsers and made phone calls on both phones. When my iPhone 5 died on Saturday night, the 5C had 17% battery power left.

First, let’s tackle the camera’s low-light performance. The shots we took with the 5s were consistently better than what we took with the 5: they were sharper, with finer details, more natural colors and far less noise. As you might expect, our daylight shots were roughly on par, though there were a few times when the 5s won out by a slight margin, offering just a little more detail. All told, the 5s plays in the same league as all those other flagships with a bigger emphasis on imaging.

– 5c final thoughts:

We’re happy with the iPhone 5c in terms of performance and battery life, but we’re longing for a better camera and a larger screen. The iPhone 5s addresses the former, but typing on any iPhone feels awfully cramped when you’re used to displays that measure 4.3 inches (and bigger, even). Maybe next time? If you’re using an iPhone 4s or anything older, you can’t go wrong upgrading to either the 5c or the iPhone 5s. We think most buyers will pick the iPhone 5c for the price and color choices alone, while the iPhone 5s will appeal to power users and gamers. iPhone 5 owners are probably better off sticking with iOS 7 or picking up an iPhone 5s instead of getting an iPhone 5c. And, if all else fails, there are always next year’s iPhones.

Personally I’d prefer the iPhone 5s simply because of its more modern platform, even if I were recommending a device for someone else not as concerned with performance. Supporting the latest ISA (which will probably stick around for a while) and OpenGL ES 3.0 are both important if you’re going to be keeping your phone for a very long time and plan on using it for more than just the basic first party apps.

As I said before though, if your plan all along was to buy an iPhone 5 – the iPhone 5c is a clear substitute good. I don’t expect that we’ll see an even cheaper version, but I am excited for what happens when the 5s hardware waterfalls into the 5c replacement next year.

Apple throwing its hat into the multi-device race marks a very important change for the company. I’ve always believed that the smartphone space would end up looking a lot like the PC industry, or in Apple’s case, the Mac business. Apple presently offers a handful of Mac notebooks, and I see no reason why Apple will stop at two with the iPhone.

The technology behind the Touch ID sensor is incredibly technical, but it’s incredibly easy to use and, more importantly, set up. It works effortlessly too: resting your finger on the Home button opens your phone with zero delay and in time you will wonder how you ever lived without it.

– On iPhone 5s in general:

In many ways Apple has released a phone for tomorrow rather than today. That’s a hard sell, in truth. The Touch ID scanner is yet to be fully realised, as are the A7 and M7 processors and the 64-bit support. It’s all a bit “what if” at the moment.

The iPhone 5C is not a flagship product – Apple’s iPhone 5S is for that – nor does it fix any of the annoying niggles you’ve perhaps started to feel with your current iPhone, but if you are looking to upgrade from the 4 or the 4S, want to stick with Apple, but can’t justify the 5S and its price, then this colourful option is could to be perfect for you. Despite initial reservations we love the iPhone 5C – it’s colourful, joyful, capable, and just works.

Once registered, you simply hold your finger on the iPhone, and it should unlock very quickly. It’s about as fast as swiping to unlock without a passcode, and much faster than entering even a simple four digit code. As Apple is fond of saying, “it just works,” recognizing your registered fingerprints regardless of how you place your digit on the sensor for the most part. I did encounter a few rare “try again” messages, but the frequency of those decreased over my time with the phone until they were non-existent, something which Apple says is due to the sensor being able to improve its success rate by learning more about your print over time.

– On the new True Tone flash:

Apple’s better camera hardware extends to the new ‘True Tone’ flash, a dual LED flash with both white and amber tones, which can match ambient light and also combine both tones in varying degrees to better reflect the environment. This is supposed to result in subjects which are less washed out when you’re taking photos in dark conditions with the flash turned on. In practice, I still found that the best solution was to leave the flash off, but as you can see from the side-by-side of my iPad mini case, the iPhone 5s flash (on left) does a much better job at rendering natural lighting than does the iPhone 5c’s (right).

It was almost immediate. It’s much quicker than entering in the passcode manually and all I have to do is rest my thumb on the Home button, which contains the fingerprint sensor.

In addition to the speed, the location of the sensor is key. There is no extra movement needed to activate fingerprint reading. That decision was vital in making the fingerprint sensor work for users—if you have to move to make it work, it may not be worth using.

Of course, you can still have a manual passcode. If you do, you are required to type this in the first time after you restart the device, and if something ever happened to your fingerprint, you have a way to access the phone.

Setting up a fingerprint is as easy as resting your finger on the Home button and following the onscreen instructions. The button will vibrate when it’s reading; lift your finger and rest it on the button again; and repeat until it’s done. Very simple.

On iPhone 5c:

There is absolutely no give to this phone at all. It doesn’t bend or buckle anywhere in the casing, which is what you want, obviously. It feels as solid as the 5s.

Like the GPU that bears the graphical strain from a computer’s processor, the new M7 Coprocessor takes the weight of motion measurements – compass, accelerometer and gyroscope – away from the all-new A7 CPU.

Apple claims this will provide a 6x power saving for (iOS 7-updated) apps that record motion – Nike+, Strava, Moves, etc – but this dedicated chip can also tell what state of movement you’re in and will adjust the iPhone 5s accordingly.

To test this, we used Apple Maps to plot an A to B route that required driving and walking. Upon reaching our destination, and exiting the car, the navigation switched from car to foot, taking us down one-way streets that wouldn’t have been possible in a motor.

If the Coprocessor is clever enough to know where you are and what you’re doing (to an extent), it could pave the way for the next wave of apps and features. One example we were given was this: if your iPhone 5s is put in a gym locker while you pump iron, it knows that a) you’re not using it b) there’s no network coverage c) it’s stationary.

The iPhone could then power itself right down, switching off 3G/4G, the screen and so forth until the time it’s picked up again, where it would come back to life, ready to take that call from your PT asking why you sat in the sauna for two hours rather than making yourself sick doing burpees.

I’m tempted to call the iPhone 5S the iPhone 5P, for “potential.” This is Apple’s half-step year, a rebuilding year. It’s telegraphed by the name itself: adding an “S” versus giving the phone a whole new name. The 5S introduces technologies that could transform the future of iOS as a computing platform, and maybe pave the way for future products in 2014. But it doesn’t manifest these changes right off the bat. Its promises haven’t come to fruition yet.

– Touch ID works with toes:

A few previous smartphones have added fingerprint sensors before, like the Motorola Atrix, but those were more awkward bars that needed finger-swiping. The Touch ID-enabled home button feels invisible; it works with a tap, can recognize your finger from many angles, and feels like it has less of a fail rate than fingerprint sensors I’ve used on laptops. It’s impressive tech. It worked on all my fingers, and even my toe (I was curious).

– Who is the 5c for?

Much like the White MacBook was to Apple laptops, the iPhone 5C feels like a perfect cover-all-your-needs smartphone, offering the average person a complete set of tools to get everything done. The extras on the iPhone 5S aren’t necessarily ones you’ll miss: unlike like last year’s leap from the iPhone 4S to iPhone 5, all the basic requirements are covered.

Of course, a $99 iPhone isn’t anything new. Apple’s been selling “last year’s iPhones” for years at a hundred-dollar discount alongside whatever new versions are sold. For the past 12 months, 2011’s iPhone 4S sat in the $99 spot; it’s now offered as a free phone with a new contract, in a take-it-or-leave-it 8GB version. But Apple’s never offered a $99 iPhone this good, and with a redesign to boot.

Those who don’t care about the latest and greatest graphics or camera quality, or are due for an upgrade — like my mom — would be a perfect fit for the iPhone 5C. It’s a good year to make an upgrade if you haven’t done so recently, because both the 5C and 5S are very polished phones.